Coccolithophores and the biological pump: responses to environmental changes

Summary

Coccolithophores, which are considered to be the most productive calcifying organisms on earth, play an important role in the marine carbon cycle. The formation of calcite skeletons in the surface layer and their subsequent sinking to depth modifies upper-ocean alkalinity and directly affects air/sea CO2 exchange. Recent work indicates that the productivity and distribution of coccolithophores are sensitive to CO2-related changes in environmental conditions, both directly through acidification of surface seawater and indirectly through increasing upper-ocean thermal stratification. To assess possible responses of this group we examine the physiology and ecology of coccolithophores with regard to expected environmental changes. Potential feedbacks to atmospheric CO2 increase, as could arise from changes in photosynthesis and calcification as well as from a shift in the dominance of coccolithophores, may be crucial when trying to forecast future climate change.